Many physiological conditions can bring on a condition known in laymen's as "frozen-shoulder", known technically in medical terms as Adhesive Capsulitis. This condition causes a restricted range of motion of the shoulder due to the contracture of tendons, muscles, ligaments and the capsule surrounding the joint. The condition can be brought about by a fall, the tearing of the rotator cuff, surgical repair of the rotator cuff, fracture of the Humerus or bursitis, etc. The condition is brought about because the tendons and muscles surrounding the joint capsule and rotator cuff shrink down and tighten up. This condition is most prevalent in the 35-75 year age bracket.
The shoulder is formed where the clavicle, scapula and humerus join. The joint formed is a ball-and-socket type articulation between the proximal humerus and the glenoid cavity of the scapula. The socket is shallow, and the joint capsule is loose-fitting. As a result of this construction, the joint permits a wide range of motion but is subject to poor stability and strength.
The shoulder is capable of three general types of motion: abduction and adduction, flexion and extension; and rotation. Aduction and adduction are movements of the arm away from and toward the median axis, or long axis, in the median plane of the body. The median plane of the body is defined by the front or back of the body in a straight position. Aduction is movement away from the median axis, such as raising an arm laterally or sideways. Adduction is the opposite movement, i.e., movement toward the median plane of the body. Rotation is turning the arm about its long axis as if on a pivot. External rotation is rotation away from the median axis of the body and internal rotation is rotation toward the median axis of the body.